In her 90-degree classroom, Hawaii teacher Sharon Nichols is so desperate to keep her third-graders cool that she walks around the classroom spritzing them with ice water.

Like virtually all schools in the normally temperate state, her building lacks air conditioning, and that’s been fine in the past. But Nichols and other Hawaii teachers say it’s been so hot this year that students have showed symptoms of heat exhaustion and had to go to the school nurse.

"I just worry about the kids that start looking sickly and tired in my class," Nichols said. "It’s very hard to focus. I’m up here teaching, and I’m telling the kids ‘Come on, wake up,’ and I’m falling asleep myself."

The Hawaii teachers union says if it’s too hot to pay attention, it’s too hot to go to school. Its president is calling on the state to establish "heat days" — like snow days — and cancel school when it’s too stifling to learn.

The move comes during a particularly scorching year in the state. Temperatures in Honolulu reached record highs at least 25 times in the last year, according to the National Weather Service, and experts say Hawaii’s cooling trade winds have been declining for decades.

"What modulates the weather here in Hawaii strongly is the temperature of the ocean water," said Chris Brenchley, a meteorologist with the National Weather Service. "Our surrounding ocean waters are running anywhere from 2 to 4 degrees Fahrenheit above normal."

That has led to air temperatures that are 2 to 3 degrees above normal, he said.

Unbearably hot classrooms prompted Corey Rosenlee, president of the Hawaii State Teachers Association, to suggest the "heat days" idea. Around the country, some districts such as Denver Public Schools canceled school during extremely hot days and adjusted their calendars to minimize heat in the classroom.

"My first priority is putting air conditioning in our classrooms, because I do not want kids missing school because it’s too hot," said Rosenlee, who described students fighting to sit near the fans when he was a classroom teacher. "You put 30 to 40 bodies in a room that are moving, and they are all little furnaces."

Nichols, who teaches at Honowai Elementary School in Waipahu, started an online fundraising campaign to get an air conditioner in her classroom.

At James Campbell High School on Oahu, where about 20 percent of the classrooms are air conditioned in a school serving more than 3,000 students, eleventh-grader Sydney May fanned herself with a vocabulary handout as a classmate rested his head on his desk in the 90-degree classroom. May said she worries that students in air conditioned classrooms have an advantage.

"I’m focused on how hot I am, instead of learning," May said after class. "I feel like I’m not obtaining as much information as I can."

While an official count found that 94 percent of schools in Hawaii don’t have air conditioning, some schools have added units on their own. The Hawaii Department of Education is planning to add air conditioning to a list of priority schools, but many facilities are more than 60 years old and would need new windows and electrical upgrades to handle the load, said Brent Suyama, a spokesman for the department. They are also conducting a heat abatement study, and have installed a photovoltaic air conditioner in one school with good results, he said.

The state’s public schools utility bill costs more than $60 million per year, and installing air conditioning at all public schools would cost an estimated $1.7 billion while also driving up electricity costs, Suyama said.

"It’s always a battle money-wise, because there’s only so much money available," he said. "Every agency needs funds to get things done, and the Department of Education is just one of the departments."

The department is open to discussing what would constitute a heat day, and it would need to explore impacts like the number of instruction days required by law and union contracts, spokeswoman Donalyn Dela Cruz said in a statement.

At humidity levels of 60 percent, weather officials advise extreme caution when the temperature reaches 86 degrees, meaning prolonged exposure can cause heat stroke or heat cramps, Brenchley said.

Kids are especially susceptible to heat exhaustion because of their small size, and they can experience headaches, nausea and vomiting, said Paul Eakin, pediatric emergency doctor at Kapiolani Medical Center. "It’s definitely far from ideal, and it’s going to definitely affect their performance at the higher temperatures," Eakin said.

Punahou High School, the private school in Hawaii that President Barack Obama attended, has air-conditioned classrooms. The units were purchased through fundraising, but the school’s $22,050 annual tuition pays for the operating costs, said Laurel Husain, spokeswoman for Punahou.

Back at Campbell, one teacher started a bottle recycling bin to raise money for fans for her classroom, May said.

"It’s outrageous. I can’t believe that we’ve allowed our schools to go on like this for so long," said Mike Wooten, a teacher at Campbell. "It gets up to 100 degrees in my classroom."